The disclosure relates generally to methods of reducing defects in ceramic articles and precursors and more particularly to methods of reducing defects in ceramic articles and precursors that are made using a batch composition containing an oil phase material.
In the production of ceramic articles, such as honeycomb-shaped articles used as substrates and filters in mobile emissions applications, it is desirable to minimize the presence of defects in ware that rise to the level of causing failure to meet ever increasingly stringent customer specifications. Such defects can include not only those observed post-firing but also those observed in post-extrusion and post-drying stages, such as green fissure. Rejection of such ware results in reduced material utilization, which is undesirable.
Defects, such as green fissures, can result from a number of causes. In the production of certain ceramic articles, such as thin walled substrates for mobile emission control, a hydrophobic material such as a fatty acid or oil is often added to the batch as a lubricant. However, because typically applied binder materials, such as methylcellulose, are frequently generally insoluble in the oil phase, this phase often has substantially lower cohesive strength than the aqueous phase. This lack of cohesive strength in the oil phase can result in a type of green fissure often referred to as an oil fissure, characterized by locally concentrated oil streaks that migrate from the bulk of the batch to the skin area during extrusion. If defects caused by such fissures are severe enough, substantial losses in material utilization can occur as well as significant down time in production facilities in order to attempt to address the problem.